Below is a link to a google photos album that relates to the discussion we've been having on FB...

First, a few photos showing the print artifacts I described (from the print last night.) The supports are "missing" as I've removed the part, but I put it back on the build plate to show the position of the part while printing. The photos were taken from the perspective on X on the left, Y (troublesome axis) on the right and Z in the back.

Also in the album are two videos:

One is a video showing me moving the carriage with the belt attached. I'm applying constant pressure to move the carriage and you can hopefully see and hear the resistance.

Another is showing the carriage, with the belt removed, being dropped. The motion is smooth and takes about 2 seconds.